Gear finishing machine



Feb. 5, 1935. I E. w. MILLER I 1,990,239

GEAR FINISHING MACHINE Filed Aug. 13, 1932 8 Sheets-Sheet 1 1935 E. w. MILLER I 1,990,239

GEAR-FINISHING MACHINE Filed Aug. 15, 1932 8 Sheets-Sheet 2 Feb. 5, 1935. E, w MlLLER I 1,990,239

GEAR FINISHING MACHINE Filed Aug. 13, 1952 8 Sheets-Sheet 3 Feb. 5, 1935. E. w. MILLER 1,990,239

GEAR FINISHING MACHINE Filed Aug. 15, 1932 T 8 Sheets-Sheet 4 y 53 mg? Ix 2 Zdmid%/%Zfew Feb. 5, 1935. Y E. w. MILLER 1,990,239

v I GEAR FINISHING MACHINE Filed Aug. 13, 1932 8 Sheets-Sh'et' 5.

Feb. 5, 1935. I I5. w. MILLER 1,990,239

' I u'rEAR FINISHING MACHINE I Filed Aug. 15, 1952 8 Sheets-Sheet 6' Feb. 5, 192.5. E. w. MILLER 1,990,239

' I GEAR FINISHING MACHINE Filed Aug 15, 1932 8 Sheets-Sheet 7 jam? @zzg/W w ww i Feb. 5, 1935. E. w. MILLER 7 1,990,239

I I GEAR FINISHING MACHINE Filed Aug. 15,4952 7 8 Shets-Sheet 8 Patented Feb 5, 1935 UNITED STATES GEAR FINISHING MACHINE Edward W. Miller, Springfield, Vt.', assignor to The Fellows Gear Shaper Company, Springfield, Vt., a corporation of Vermont Application August 13, 1932, Serial No. 628,710

19 Claims.

The present invention relates to the art of finishing gears to correct form and dimensions by running them in mesh with other gears as finishing tools; preferably with abrasive action enhanced by the application of fine abrasive particles between their intermeshing teeth. For convenience of description I will generally refer to the machine herein as a lapping machine, to the gear shaped tools as laps, and to the action performed as lapping; but without intent thereby to limit the invention as to the uses to which it may be put. That is, by the selection of suitable tools, and the use or non-use of abrasive, the same machine may either lap, burnish or scrape the work, or perform any combination of these actions.

The objects of the invention are to provide an improved machine by which a combination of radial and axial rubbing movements may be imparted to the work relatively to the tools; to enable the same machine, by selection of proper tools, to finish either spur or helical gears; when treating helical gears, to enable the helix angle, as well as the tooth forms, to be finished accurately, and correct it if originally inaccurate; to enable the teeth of either spur or helical gears to be finished with a laterally crowned or bulging formation between their ends; and to provide other improvements, the nature and character of which appear from the following description and the appended claims. An illustrative machine embodying the means for accomplishing these aims is described in the following specification and shown in the accompanying drawings, in which, I

Fig. l is a front elevation of the machine with the housing and work spindle cut away to show the tools and work piece;

Fig. 2 is'a left end elevation partly in section on line 22 of Fig. 1;

Fig. 3 is a rear elevation;

Figs. 4 and 5 are detail sections on and 55, respectively, of Fig. 3;

Fig. 6 is a vertical cross section of the machine taken on line 66 of Figs. 2 and '7;

Fig. '7 is a vertical longitudinal section taken on line '77 of Fig. 6;

Fig. 8 is a vertical cross section on line 88 of Fig. 7;

Fig. 9 is a longitudinal detail section on line 9-9 of Fig. 8;

Fig. 10 is a diagrammatic axial section of a helical gear showing the nature of its tangent contact with .a mating gear on a parallel axis;

Figs. 11, 12 and 13 are fragmentary views of a line 44 tooth of the work piece in successive mesh with different ones of the tools.

Like reference characters designate the same parts wherever they occur in all the figures.

A gear in process of being finished is shown at 10. It is in simultaneous mesh with three tools, 11, 12 and 13, which are clamped and keyed on shafts 14, 15 and 16, respectively. These tools are accurate master gears conjugate to the particular work piece being finished. When the work piece is a spur gear, the tools likewise are spur gears, and when the work is a helical gear, the tools are also helical gears of equal and opposite helix angle.

The work piece may be any single element of a cluster gear, or an individual gear. It is mounted on an arbor 1'7 secured to an adapter 18 which in turn is set and secured in one end of a tubular work spindle 19. This spindle is positively rotated and reciprocated. It is surrounded by and parallel to the three tool carrying shafts.

By virtue of the reciprocating motion of the work spindle, a rubbing efiect is obtained longitudinally of the work. A radial rubbing effect is obtained also by the slip of the teeth as they pass into and out of mesh. In order that this effect may be as nearly as possible uniform throughout the root-to-tip extent of the tooth faces, the three tools are preferably mounted at respectively different center distances from the work spindle, (as, for instance, the tool 12 at a distance of 4.90 inches, tool 13 at a distance of 4.95 inches, and tool 11 at a distance of 5.00 inches) whereby they mesh with the work on respectively different pitch lines and the teeth of each slip radially across the pitch lines in the work piece of the othertwo.

Further explaining this effect, attention is directed to Figs. 11, 12, and 13, in each of which one tooth of the work piece, designated 10a, is

shown on an enlarged scale, and fragments of two flanking teeth. of the respective tools 11, 12 and 13 are designated respectively as 11a and 11b in Fig. 11, 12a and 12b in Fig. 12, and 13a and 13b in Fig. 13. The circular arcs P and P designate the pitch lines of the work and of the tool 11 respectively. The points on the faces of tooth 10a intersected by line P, and the points on teeth 11a. and 11b intersected by the line P roll together without radial slip; but there is radial slip at points inside and outside of these pitch lines. correspondingly the arcs P and l? in Fig. 12 designate the pitch lines on which the work and tool 12 roll together without slip; and in Fig. 13 the arcs P and P designate the pitch lines of the work and the tool 13, on which these latter gear elements roll without radial slip. Of the three pitch lines thus established in the work, the line P is at a maximum distance from the axis of the work, P at a minimum distance from the axis, and P at an intermediate distance. Thus, assuming that the direction of drive is that indicated by the arrows applied to the tooth 100., the left hand faceof this tooth is rubbed by tooth 11a radially across the pitch lines P and P by the to'oth 12a across the pitch lines P and P and by the tooth 13a across the pitch lines P and P The direction in which the tooth 11a slips on the work in crossing the intermediate pitch line P is opposite to that of the tooth 12a across the same pitch line; occurring in the one case before the contacting tooth faces reach the pitch point, and in the other case after they have passed the pitch point. When the drive is in the opposite direction, the right hand faces of tooth 10a are correspondingly acted on by the teeth 11b, 12b and 13b. In this machine, as described later on, the work piece drives the tool against frictional resistance. Of course all the teeth of the work piece are similarly treated by different teeth of the respective tools. The several tools are designed with tooth forms all conjugate to the same mating tooth, in accordance with well known principles of gearing. Thus, in the case of involute gears, the side faces of the teeth of all the tools are involute curves developed from the same base circle.

The phase of the machine just described is essentially the same as one of the features of the gear finishing machine disclosed in my pending application filed January 26, 1932, Serial No. 588,913, and the present application is, to the extent of said common subject matter, a continuation of said prior application. Other features of the invention are not limited to the detail just described, and are intended to be protected hereby in combination with any suitable tools, whether like or unlike to one another and whether at equal or unequal center distances from the work.

Shaft 14 of the tool 11 is mounted rotatably, but withheld from motion otherwise, in fixed bearings 20 and 21 in the framework of the machine. The other shafts 15 and 16, however, are supported with provision for angular movement,

each in a self alining bearing 22, and each is adjustable angularly in a plane tangential to an arc concentric with the work spindle. The plane in which shaft 15 isthus adjustable is indicated by the line AA ofrFig. 1, and that in which the shaft 16 is adjustable by the line B-B. Such adjustment changes the inclination of the tool with respect to the work, and is effected in each instance about the bearing 22 as a fulcrum.

In order that the displacement bodily of the tool in'consequence of such adjustment may be a minimum, the bearing 22 is located as close as possible to the tool. In the present machine, in the interest of simplicity of design, this bearing has been located at one side of the tool, but it is within the scope of my contemplation and the protection which I claim to locate the axis of adjustment midway between the end faces of the tool. In other words, this phase of the invention comprises so mounting the tool that it may be adjusted angularly about an axis perpendicular both to its own axis and'to that of the work piece, whether such axis of adjustment is in the middle plane of the tool or at the minimum distance from such plane consistent with simplicity of design.

This capacity of adjustment is an important factor of the invention. When used in lapping helical gears it providesa means for correcting inaccuracy in the helix angles of such gears, within thelimits of error of gear cutting machines, and the limits of distortion of hardened helical gears due to heat treatment. Helical gears conjugate to one another on parallel axes make tangent tooth contact along a line which is inclined lengthwise of the tooth from end to end. Fig.

10 shows at C the projection on a radial plane of the gear of the line at which tangency occurs when the gear teeth are at the pitch point. The line shifts radially in or out as the tooth revolves in one direction or the other from the pitch point. Thus by so inclining the tool as to intensify the pressure at one end of the tooth, and relieve it at the other end, the helix angle of the gear teeth being finished may be modified sufficiently to correct errors or distortions of the character above mentioned.

' For effecting such adjustments the bearing 23 of shaft 15, and bearing 24 of shaft 16, (Figs. 6 and 7), remote from the fulcrum bearing, are

contained respectively in holders 25 and 26. The

holder 25 is carried by a bar or shaft 27, which is splined to slide in a bearing 28, and extends also through a second bearing 29. The line of movement of this rod or shaft is in the same plane with the line A-A previously mentioned. It is tangent to an arc concentric with the work spindle. Said bar or shaft 27 is provided with a screw thread 30 which is engaged by a nut-31 confined against endwise movement by flanking portions of bearing 29. This nut is formed externally as a gear or worm wheel 32 with which meshes a worm 33, on a shaft 34 (Fig. 2) which extends to the front of the machine and there carries a hand wheel 35. A spring 36 surrounding the shaft 37 and reacting between a collar 37 thereonand the adjacent end of bearing 29, takes up backlash between the nut and screw.

The holder 26 for bearing 24 is carried by a similar shaft 38, movable endwise, tangentially of the work spindle, in. the plane BB, and is actuated similarly by a nut 39, worm 40, shaft 41, hand wheel 42, and spring 43.

When both adjustable laps are so adjusted for the correction of helix angles, they are adjusted in the same sense or direction with respect to the helix angle of the work. In other words, the displaceable bearings 23 and 24 are shifted tangentially of the work spindle either both clockwise or both counter-clockwise (with reference to Fig. ,6). However, they may be adjusted oppositely to one another, in the sense herein defined, so as to make the teeth of the work narrower at the ends than at the middle, thus producing a crowning effect suited to cause quieter running of the gears in service and to avoid ill effects of slight misalinement of the shafts or pivots with which they are used.

Spur gears likewise may be treated for correc- 'tion of distortion or for creation of a crowning Power is provided to rotate and reciprocate the work spindle from a single prime mover, which may be an electric motor 44 mounted in a shaft 45 which may behereconsideredasthe main shaft of the machine. "Hie-main;- drives an intermediate shaft by means of a helical gear pair 47 and48; intermediate shaft, by means of changeable gears 49 and 50, drives a shaft 51 which is axially alined with the work spindle 19 and drives the latter by means of a sliding clutch 52, 53. The member 52 of this clutch projects into the adjacent end of the tubular spindle and is provided with external spur gear teeth or ribs complemental to internal teeth on the annular clutch member 53 which is secured to the adjacent end of the work spindle. This character of clutch provides scope for any feasible length of reciprocation of the work spindle, coincidentally with its rotation, and also for placement of the spindle in different positions of longitudinal adjustment.

Reciprocation of the spindle is effected by a sector 54 (Fig. '1) meshing with encircling rack teeth 55 on the spindle and carried by a shaft 56 (Fig. 8) on which is secured a crank arm 57. A wrist pin 58 on arm '1 is coupled by a connecting rod 59 to a crank pin 60 carried by shaft 61 which is driven by the main shaft through a helical gear pair 62, 63, shaft 64, changeable gears 65, 66, shaft 6'1, and helical gears 68, 69, (Figs. 3, 5, 8 and 9).

Crank pin 60 is mounted adjustably in a radial slot in the face of a crank disk '10 on shaft 61, whereby the stroke of the spindle may be varied or adjusted.

A brake load is applied to the tool shafts to furnish a lapping pressure of regulatable amount. Suitable brakes for this purpose are shown in Fig. '1 as applied to shafts 14 and 15, being both alike, and a similar one is applied to shaft 16, but not shown here. Each brake comprises a disk '71 splined to the tool shaft and a brake shoe in the form of a disk or plate '12 which is pressed against disk '11 by spring '13 and is restrained from' rotation by a dowel '14. The brake shoe is slidable on a sleeve '15, which is keyed to the tool shaft and has a reaction flange '16; and the springs '13 and dowel '14 are seated in an annular holder '17 which surrounds the sleeve 15, reacts against flange '16, and carries an outstanding lug or fork "18 which embraces a stud '19 mounted in a stationary part of the framework. This stud, holder, and dowel, provide an anchorage to prevent rotation of the brake shoe. Only the anchorage stud and forked lug for the brake of shaft 14 are shown in these drawings. Those for the brakes on shafts and 16 have a scope of lost motion sufficient to permit the angular or skew adjustment of these shafts, previously described. They may be arranged at any side of their respective shafts with equal effect. Adjustment of the braking pressure is afforded by making the disk '11 slidable on the shaft and providing for a range of axial movement of both the disk and brake shoe; the nut 80 which clamps the disk on the shaft serving as a means for compressing or relaxing the springs. It will be understood that a number of springs '13 are provided with such distribution around the axis of the shaft as to move the brake shoe without cramping tendency. The pressure so produced causes one side only of each tooth of the work piece to be treated in the manner described. The teeth are treated on the opposite side either by reversing the direction of drive, or by turning the-base of the-machine, one. pulley on a counter shaft, etc.- 'The primemovea'rotates, by means of a belt and pulley, or. andjsprocket drive,

shaft-1, 46 (Figs: 3"ahd, 4)'

j and." clearness -"to inform andthe f the workpiece endfore nd andreplacing it on The nature of a suitablejframework and mountings for the shafts and other partsofthe' machine without further explanation,

Variations and modifications'in. the construe 1o tion and. arrangement, of the machineand its several parts and sub combinations' maybe made within the scope of the principles herein disclosed v and of the protection claimed.

What I claim and desire to secure by Letters Patent is:

1. A gear finishing machine comprising means for supporting a gear to be finished with provision for rotating about its axis, means for mounting a tool in the form of a gear conjugate to the work with provision for rotation in mesh with the work piece about an axis at one side of and substantially parallel to the axis of the latter, and means for effecting a relative adjustment between the work piece and tool angularly about an axis perpendicular to the axes of both between a position of exact parallelism and other positions more or less askew to one another.

2. A gear finishing machine comprising means for supporting a work piece with provision for rotation about its axis, a series of master gears conjugate to the work piece mounted to rotate on their own axes and located at different sides of, and in mesh with, the work piece, and means for adjusting certain of said master gears angularly about axes perpendicular both to their own respective axes and to the axis of the work piece.

3. A gear finishing apparatus comprising means for supporting a work piece with capacity for rotating about its axis, a tool in the form of a master gear conjugate to the work piece mounted to rotate about an axis at one side of and substantially parallel to that of the work piece and having tangent contact with the work throughout substantially the overlapping length of their respective intermeshing teeth, and means for effecting relative angular adjustment between the work piece and tool so as to set them either exactly parallel or more or less askew to one another.

4. A gear finishing machine comprising means for supporting a work piece rotatably, a shaft substantially parallel to the axis of the work piece, a tool in the form of a master gear conjugate to the work piece and adapted to make tangent contact therewith over substantially the entire overlapping length of their intermeshing teeth, mounted on said shaft, and means for shifting said shaft angularly in a plane tangent to an arc coaxial with the work piece.

5. A gear finishing machine comprising means for supporting a work piece rotatably, a shaft substantially parallel to the axis of the work piece, a tool in the form of a master gear conjugate to the work piece and adapted to make tangent contact therewith over substantially the entire overlapping length of their intermeshing teeth, mounted on said shaft, and means for shifting said shaft angularly in a plane tangent to an arc coaxial with the work piece about a fulcrum in close proximity to the mid zone of the tool.

6. A gear finishing machine comprising means for supporting a work piece rotatably, a tool constructed as a master gear conjugate to the work piece and adapted to make tangent contact between meshing teeth of the work piece and tool throughout substantially the entire extent of the areshown by the drawings with-sufiicient fullness the machine builder, 1.

how to put the in-;-."' -vention-.to, practical operation.

overlapping length of such teeth, a shaft sub-- stantially parallel to the axis of the work on which said [001 is mounted, an angularly self alining bearing for said shaft adjacent to the tool, a second bearing for the shaft at a distance from the tool. and means for adjusting the last named bearing in a plane tangent to an arc coaxial with the work piece.

'7. A at an finishing machine comprising a work spindle, a tool shaft adapted to carry a finishing tool in the form of a master gear, a bearing for said tool shaft adjacent to the part thereof which cariiesthe tool, organized and arranged to permit angular movement of the shaft-about a fulcrum axis located in said bearing, a holder surrounding and having abearing for said shaft at a distance from the first named bearing,. said holder being movable back and forth in a plane radial to the shaft and tangential to an arc coaxial with the work spindle, and means for so moving the holder whereby to place the tool more or less askew to the work piece.

8. A gear finishing machine comprising a rotatable work spindle adapted to carry a gear to be finished with its axis alined to that of the spindle, a plurality of tool carrying shafts arranged on different sides of the work spindle with their axes parallel to the axis of the latter, finishing tools in the form of master gears carried by the several shafts to mesh with a work piece on the work spindle, and means for angularly inclining two of said shafts about fulcrum points adjacent to the tool locations on said shafts in either direction from their positions of parallelism with the work spindle, each in a plane diametral to its axis and tangential to an arc coaxial with the work spindle.

9. A gear finishing machine comprising a work spindle adapted to carry a gear to be finished, means for positively rotating and reciprocating said work spindle, a finishing tool consisting of a gear mounted to rotate in mesh with the work piece, and formed to make tangent contact throughout substantially the entire overlapping length of their intermeshing teeth when arranged on an axis parallel with that of the work spindle, means for frictionally impeding rotation of the tool, and means for inclining the tool to a skew angle with respect to the work piece.

10. A gear finishing machine comprising a tubular work spindle rotatably and reciprocatably mounted, a driving shaft axially alined with said spindle, a clutch element carried by said shaft extending into one end of the spindle and having external teeth or ribs, a complemental annular clutch element secured to the spindle having internal teeth in longitudinally slidable engagement with the teeth of the first clutch element. rack teeth carried by the work spindle, a gear segment meshing with said rack teeth and oscillatable to reciprocate the spindle thereby, and

' driving means for simultaneously rotating said shaft and rocking said segment at a prescribed ratio.

11. In a gear finishing machine as set forth in claim 10, the combination with the elements there claimed, of tool shafts arranged around the work spindle, and finishing tools in the form substantially of master gears carried by said shafts.

12. In a gear finishing machine as set forth in claim 10, the combination with the elements there claimed, of tool shafts arranged around the work spindle, finishing tools in the form substantially of master gears carried by said shafts, and

braking means a p ied to said tool shafts for resisting rotation thereof.

13. A gear finishing machine comprising a tool in the form of a master gear adapted to run in mesh with agear to be finished on an axis parallel to the axis of the gear, and means for inclining the axis of said tool to either side of its position of parallelism with the gear axis, in a plane tangent to an arc concentric with the gear axis.

14. The method of finishing gears with a crowning formation between the ends of their teeth which consists in running such a gear in mesh with a conjugate master gear, inclining the axis of the master gear to an acute angle with a line parallel to the axis of the work piece in a plane tangent to an arc concentric with such axis, and then inclining the tool axis to the other side of such 118,111 the same plane, and reversing the direction of drive between the work and master gear.

15. A gear finishing machine comprising a rotatable work spindle, a rotatable tool spindle mounted beside the work spindle, a finishing tool in the form of a master gear on said tool spindle adapted to mesh with a gear carried by the work spindle, separated bearings for one of said spindles, one of such bearings being in close proximity to the common plane of the tool and work piece and constructed to permit angular displacement of the spindle supported thereby, and means for displacing the other of said bearings in directions tangential to a circle concentric with the axis of the other spindle.

16. A gear finishing machine comprising a rotatable work spindle, a rotatable tool spindle mounted beside the work spindle, a. finishing tool in the form of a master gear on said tool spindle adapted to mesh with a gear carried by the work spindle, separated bearings for one of said spindles, one of such bearings being in close proximity to the common plane of the tool and work piece and constructed to permit angular displacement of the spindle supported thereby, a bar having a holder in which the bearing more remote from said common plane is contained, said bar extending and being movable endwise in a direction tangent to a circle concentric with the axis of the other spindle, and means for shifting said bar endwise whereby to incline the spindle which is supported by'said bearing, more or less with respect to a plane radial to the other spindle.

17. A gear finishing machine comprising a rotatably mounted work spindle, two shafts mounted substantially parallel to said spindle on different sides thereof, tools in the form of master gears mounted on said shafts in position to mesh simultaneously with a gear mounted on the work spindle, separated bearings for. each of said shafts, one of which is arranged close to the tool thereon and is constructed to permit angular displacement of the shaft supported thereby between a position in parallel with the work spindle and other positions more or less askew to the work spindle, individual holders for the bearings of the respective shafts which are more remote from the tool, said holders being displaceable tangentially with respect to the work spindle,

and independent means for so displacing each of i said holders whereby to incline either shaft independently to either side of its position of parallelism with the work spindle. I

18. A gear finishing machine comprising a work spindle adapted to carry a gear to be finished, means for positively rotating and reciprocating said work spindle, a finishing tool consist- (ill - crum bearing near the tool, a bearing for said shaft remote from the tool, means for shifting said bearing tangentially of the work spindle, a friction brake element secured to the shaft, 'a spring pressed brake shoe engaging said brake element, and means for preventing rotation of said shoe having a lost motion connection with a stationary part of the machine organized to' exert such restraint on the brake shoe while permitting displacement of the shaft.

19. In a gear finishing machine, the combination with work and tool spindles adapted to carry respectively a gear to be finished and a tool in the form of a master gear, of means for driving one of said spindles rotatably, and a brake frictionally resisting rotation of the other spindle; said brake comprising a disk fixed to its spindle, a brake shoe adapted to bear on the brake disk, an armular holder surrounding the spindle, springs supported by and reacting against said holder to force the brake shoe against the disk, a key member arranged between the holder and brake shoe to prevent rotation of one relatively to the other, and fixed anchor means on the machine engaged with the holder to prevent rotation thereof with the shaft.

EDWARD W. MILLER. 

